Dermatology Flashcards
What are the main causes of Urticaria?
Idiopathic
Food
Iatrogenic
Contact
Insect bites
Viral
Parasitic infections
Autoimmune
Hereditary
Explain the pathophysiology behind Urticaria?
Local inflammatory response causes the release of histamine from mast cells.
This causes vasodilation of local capillaries and venues leading to swelling of the superficial dermis. This raises the epidermis causing itchy wheals.
What are the cytokines involved in Urticaria?
Histamine
Leukotrienes
Prostaglandins
What is the management for Urticaria?
Antihistamines (eg. Chlorphenamine 4mg)
Corticosteroids can be prescribed for severe Urticaria and angioedema
What is Erythema nodosum?
This is localised inflammation of subcutaneous fat.
It presents as discrete tender nodules which may become confluent and are commonly found on the shins.
What are the main causes of Erythema nodosum?
Pregnancy
IBD
Sarcoidosis
Group A beta-haemolytic Streptococci
Primary TB
Malignancy
Chlamydia and Leprosy
What is the management of Erythema nosodum?
Conservative management. It is a condition that is usually self-resolving.
What is Erythema multiforme? What usually causes this condition?
This is an acute self-limiting inflammatory condition that is caused by Herpes simplex virus.
Mucosal involvement is absent or limited to one surface.
What is Stevens-Johnson syndrome?
What is its appearance on Histology?
It is a mucocutaneous necrosis with at least two mucosal sites involved.
Its appearance on Histopathology is epithelial necrosis with a few inflammatory cells.
What causes Stevens-Johnson syndrome?
It is commonly caused by medication. Examples include
- Allopurinol
- Carbamazepine
- Phenytoin
- Lamotrigine
How are Stevens-Johnson syndrome and Toxic epidermal necrosis similar?
They have overlapping features which include prodromal illness.
What is Toxic epidermal necrosis?
This is a drug-induced acute severe disease characterised by extensive skin and mucosal necrosis with systemic toxicity. Full thickness epidermal necrosis occurs with sub epidermal detachment.
How do you manage TEN and SJS?
Early recognition and escalation to a senior.
Stop offending/causative substance.
Full supportive care to maintain haemodynamic equilibrium.
What is the cause of death in SJS and TEN?
Sepsis, electrolyte imbalance or multi-system organ failure.
What is the name of the condition whereby a patient presents with exfoliative dermatitis that covers at least 90% of the skin surface?
Erythroderma!
How does a patient with Erythoderma present?
Skin inflamed, oedematous and scaly.
General malaise.
Management of erythoderma?
Treat the underlying cause
Emollients and wet wraps to maintain skin moisture.
Topical steroids.
What is necrotising fasciitis?
A rapidly spreading infection of the deep fascia with secondary tissue necrosis.
How does necrotising fasciitis present?
Severe pain
Erythematous splitting necrotic skin
Fever
Tachycardia
Pulmonary crepitus
X-ray may show soft tissue gas.
Management of necrotising fasciitis?
Urgent referral for extensive surgical debridement.
IV antibiotics.
Mortality is 76%
What is Erysipelas?
Acute superficial form of cellulitis that involves the dermis and the upper subcutaneous tissues
What is cellulitis?
Inflammation of the deep subcutaneous tissues
What are the most common causes of Erysipelas and Cellulitis
Streptococcus. pyogenes
Staphylococcus aureus
What is the management for cellulitis?
Antibiotics (Flucloxacillin or Benzylpenicillin)
Supportive care: rest, leg elevation, sterile dressings and analgesia.
How does Staphylococcal scalded skin syndrome present?
Commonly seen in early childhood
Caused by coagulase positive Staphylococcus aureus
Perioral crusting, scalded skin like appearance that can be accompanied with bullae.
How do you treat scalded skin syndrome?
Antibiotics (penicillinase resistant penicillin, fusidic acid, erythromycin or an appropriate cephalosporin)
Analgesia
What is a Tinea infection of the trunk and limbs called? How does it present?
Tinea corporis - annular circular lesions with clearly defined, raised and scaly edge.
What is a Tinea pedis?
Athletes foot - moist scaling and fissuring in the towers, spreading to the sole and dorsal aspect of the foot.
What would you call a Tinea infection of the hand?
Tinea mannum - scaling in the palmar creases.
What would you call a Tinea infection of the scalp and how would it present?
Patches of broken hair, scaling and inflammation. This is often due to a ringworm infection.
What is Pityriasis versicoloured?
This is a scaly pale brown patch on the upper trunk that fails to tan on sun exposure. It is usually asymptomatic.
How would you manage any Superficial fungal infections?
- Diagnose with skin scrapings, hair or nail samples, skin swabs for yeast.
- Topical anti fungal agent - Terbinafine cream
- Oral anti fungal agent (itraconazole) for severe or widespread or nail infections.
Correct predisposing factors where you can
What happens if you treat a superficial fungal infection with corticosteroids?
This can cause tine incognito.
What are some risk factors for Basal Cell Carcinoma?
UV exposure
History of frequent or severe sunburn in childhood
Skin type I
Age
Male sex
Immunosuppression
Genetics
What are the different types of Basal Cell Carcinoma?
Nodular (most common)
Superficial (plaque like)
Cystic
Morphoeic (sclerosing)
Keratotic
Pigmented
How does a nodular basal cell carcinoma appear?
Skin coloured papule with surface Telangiectasia, pearly rolled edge, lesion may be necrotic/ulcerated.
What is a Squamous cell carcinoma?
A locally invasive malignant tumour of the epidermal keratinocytes or its appendages which have the potential to metastasise.
Describe the ABCDE symptoms rule for looking for an abnormal skin lesion?
A - Asymmetry
B - Border Irregularity
C - Colour irregularity
D - Diameter >6mm
E - Evolution of the lesion (change in size/shape)
What is a Melanoma?
An invasive malignant tumour of the epidermal melanocytes which has the potential to metastasise
Where are Melanomas most commonly found?
On the trunk in men and on the legs in women.
What is eczema?
Papules and vesicles on an erythematous base.
How do you manage eczema?
General measures - avoid exacerbating agents, frequent emollients and soap substitutes
Topical steroids for flare ups. Topical immunomodulators (eg. Tacrolimus) can be used as a steroid sparing agent
Phototherapy used in refractory cases
What are two known complications of eczema?
Secondary bacterial infection
Secondary viral infection
What is the management for Acne vulgaris?
Topical therapies - benzoyl peroxide and topical antibiotics (antimicrobial properties)
Topical retinoids (comedolytic and anti-inflammatory properties)
Oral therapies - oral antibiotics and anti-androgens (in females)
Oral retinoids - eg, Roaccutaine for severe acne. This can only be prescribed in specialist care.
What is Psoriasis?
A chronic inflammatory skin disease due to hyper proliferation of keratinocytes and inflammatory cell infiltration
Name some risk factors for Psoriasis?
Trauma
Infection
Drugs
Stress
Alcohol
Where is Psoriasis common?
Over the extensor surfaces and on the scalp.
How does Psoriasis appear?
Hyperkeratinisation. Well defined plaques. The lesions can be itchy, burning or painful.
What is Auspitz sign?
This is where gentle removal of scales from the surface of lesions will lead to bleeding.
What is the management for Psoriasis?
Topical therapies - Topical corticosteroids, vitamin D analogues, topical retinoids
Oral therapy can be used for extensive/severe disease - Methotrexate, retinoids, cyclosporin, mycophenolate mofetil
Phototherapy can be used in extensive disease refractory to all other treatment.
What is a complication of Psoriasis?
Erythroderma
Infection
Name three blistering disorders of the skin
Bullous impetigo
Bullous pemphigoid
bulls vulgaris
What is Bullous pemphigoid?
This is a blistering disorder that usually affects the elderly.
The lesions are often itchy and it is due to an autoimmune reaction in the sub-epidermal split in the skin.
What is Pemphigus Vulgaris?
Blistering skin disorder that affects middle aged patients
It is intra-epidermal split in the skin
Lesions are painful
What is the management for Bullous Pemphigoid?
Wound dressings as appropriate
Topical corticosteroids
Oral steroids for widespread diseases and consider DMARD’s for more extensive disease
What is the management for Pemphigus vulgaris?
General measures include wound dressings and monitoring oral care if mucosa are involved
Oral therapies - oral high dose steroids, and consider DMARD’s.
